Numerical Investigation of AC Losses in Multifilamentary MgB₂ Wires

Magnesium diboride (MgB2) is classified as a medium-temperature superconductor, distinguished by its unique material properties that render it exceptionally suitable for a diverse array of applications, including those in industrial, medical, and large-scale scientific (”big science”) fields. Its critical temperature of 39 K positions it as an ideal candidate for applications that leverage synergy with liquid hydrogen, an increasingly pertinent energy carrier in the mid-2020s, particularly within sectors such as aerospace propulsion, maritime transport, and energy transmission. However, the escalating de- mand for superconducting technologies, coupled with the expanding spectrum of possible alternating current (AC) applications, neces- sitates a comprehensive optimization of wire performance. Like all superconducting materials, MgB2 is susceptible to losses induced by time-varying electromagnetic fields. This research work addresses these challenges by focusing on two principal objectives. First, it undertakes an in-depth investigation of the macroscopic phenomenology of AC losses, aiming to iden- tify and elucidate the various factors contributing to these losses in multifilamentary MgB2 wires, particularly those embedded within resistive and ferromagnetic matrices. A thorough understanding of these loss mechanisms is essential for mitigating losses in industrial applications that operate at frequencies exceeding those typically associated with superconductivity (50-400 Hz). Second, the devel- opment of robust numerical tools is imperative for facilitating the analysis and optimization of MgB2 wires, thereby enabling paramet- ric studies and optimization sweeps aimed at minimizing losses in AC applications. Through this comprehensive investigation, three distinct models have been developed to conduct detailed analyses of AC losses in MgB2 wires, with particular emphasis on those containing magnetic stabilizing materials.